The present invention is directed to coated recording sheets. More specifically, the present invention is directed to recording sheets particularly suitable for use in electrophotographic printing processes. One embodiment of the present invention is directed to a recording sheet which comprises (a) a substrate; (b) a coating on the substrate which comprises a binder and a material having a melting point of less than about 65.degree. C. and a boiling point of greater than 150.degree. C. and selected from the group consisting of alkyl phenones, alkyl ketones, halogenated alkanes, alkyl amines, alkyl anilines, alkyl diamines, alkyl alcohols, alkyl diols, halogenated alkyl alcohols, alkane alkyl esters, saturated fatty acids, unsaturated fatty acids, alkyl aldehydes, alkyl anhydrides, alkanes, and mixtures thereof; (c) an optional traction agent ; and (d) an optional antistatic agent.
U.S. Pat. No. 5,118,570 (Malhotra) and U.S. Pat. No. 5,006,407 (Malhotra), the disclosures of each of which are totally incorporated herein by reference, disclose a transparency which comprises a hydrophilic coating and a plasticizer, which plasticizer can, for example, be from the group consisting of phosphates, substituted phthalic anhydrides, glycerols, glycols, substituted glycerols, pyrrolidinones, alkylene carbonates, sulfolanes, and stearic acid derivatives.
U.S. Pat. No. 5,145,749 (Matthew) discloses erasable coatings for xerography paper which comprise a pigment such as calcium carbonate in a binder such as an aqueous emulsion of an acrylic polymer. The erasability of the coating is improved by replacing at least 15 weight percent of the binder with a polyalkane or polyalkene wax, such as an aqueous emulsion of a polyolefin.
U.S. Pat. No. 4,526,847 (Walker et al.) discloses a transparency for the formation of an adherent electrostatic image thereon which includes a polyester resin film sheet having an image-receiving coating of nitrocellulose, a plasticizer, a particulate material, and, preferably, an antistatic agent. The coating is applied to the film sheet from a solvent mixture of an aliphatic ester or an aliphatic ketone, and an aliphatic alcohol.
U.S. Pat. No. 3,619,279 (Johnston et al.) discloses a toner receiving member having available at an external surface a solid crystalline plasticizer to reduce the fusion power requirements when toner is fused to the receiving member. The external surface of the toner receiving member is substantially free of material plasticizable by the solid crystalline plasticizer. Typically a plasticizer such as ethylene glycol dibenzoate may be available on the surface of paper.
U.S. Pat. No. 3,561,337 (Mulkey) discloses a sheet material having a transparent backing coated with a layer containing a polymeric binder and particles of solid material which is insoluble in the binder. The refractive index of the solid material varies from that of the binder by at most .+-.0.6. The surface of the layer is ink receptive and, by printing on that surface, a transparency is obtained.
U.S. Pat. No. 3,493,412 (Johnston et al.) discloses an imaging process wherein an electrostatic latent image is developed with a thermoplastic resin toner on an imaging surface and the toner image is transferred to an image receiving surface carrying an amount of a solid crystalline plasticizer sufficient to lower the toner fusion requirements when the toner image is fused to the receiving surface.
U.S. Pat. No. 3,488,189 (Mayer et al.) discloses the formation of fused toner images on an imaging surface corresponding to an electrostatic field by depositing on the imaging surface in image configuration toner particles containing a thermoplastic resin, the imaging surface carrying a solid crystalline plasticizer having a lower melting point than the melting range of the thermoplastic resin and heat fusing the resulting toner image.
U.S. Pat. No. 4,956,225 (Malhotra) discloses a transparency suitable for electrographic and xerographic imaging which comprises a polymeric substrate with a toner receptive coating on one surface thereof comprising blends selected from the group consisting of: poly(ethylene oxide) and carboxymethyl cellulose; poly(ethylene oxide), carboxymethyl cellulose, and hydroxypropyl cellulose; poly(ethylene oxide) and vinylidene fluoride/hexafluoropropylene copolymer; poly(chloroprene) and poly(alpha-methylstyrene); poly(caprolactone) and poly(alphamethylstyrene); poly(vinyl isobutyl ether) and poly(alpha-methylstyrene); poly(caprolactone) and poly(p-isopropyl alpha-methylstyrene); blends of poly(1,4-butylene adipate) and poly(alpha-methylstyrene); chlorinated poly(propylene) and poly(alpha-methylstyrene); chlorinated poly(ethylene) and poly(alpha-methylstyrene); and chlorinated rubber and poly(alphamethylstyrene). Also disclosed are transparencies with first and second coating layers.
U.S. Pat. No. 4,997,697 (Malhotra) discloses a transparent substrate material for receiving or containing an image which comprises a supporting substrate base, an antistatic polymer layer coated on one or both sides of the substrate and comprising hydrophilic cellulosic components, and a toner receiving polymer layer contained on one or both sides of the antistatic layer, which polymer comprises hydrophobic cellulose ethers, hydrophobic cellulose esters, or mixtures thereof, and wherein the toner receiving layer contains adhesive components.
European Patent Publication 463,400, published Jan. 2, 1992, corresponding to copending application U.S. Ser. No. 07/544,577 (Malhotra), entitled "Transparencies Comprising Metal Halide or Urea Antistatic Layer," discloses a transparent substrate material for receiving or containing an image comprising a supporting substrate, an ink toner receiving coating composition on both sides of the substrate and comprising an adhesive layer and an antistatic layer contained on two surfaces of the adhesive layer, which antistatic layer comprises mixtures or complexes of metal halides or urea compounds both with polymers containing oxyalkylene segments.
Copending application U.S. Ser. No. 07/806,064 (Malhotra et al.), entitled "Coated Recording Sheets for Electrostatic Printing Processes," discloses a recording sheet which comprises a base sheet, an antistatic layer coated on at least one surface of the base sheet comprising a mixture of a first component selected from the group consisting of hydrophilic polysaccharides and a second component selected from the group consisting of poly (vinyl amines), poly (vinyl phosphates), poly (vinyl alcohols), poly (vinyl alcohol)-ethoxylated, poly (ethylene imine)ethoxylated, poly (ethylene oxides), poly (n-vinyl acetamide-vinyl sulfonate salts), melamine-formaldehyde resins, urea-formaldehyde resins, styrenevinylpyrrolidone copolymers, and mixtures thereof, and at least one toner receiving layer coated on an antistatic layer comprising a material selected from the group consisting of maleic anhydride containing polymers, maleic ester containing polymers, and mixtures thereof.
While the above materials and processes are suitable for their intended purposes, a need remains for recording sheets particularly suitable for use in electrophotographic applications. In addition, a need remains for recording sheets upon which the toner materials commonly employed in electrophotographic Imaging processes exhibit improved adhesion. Further, there is a need for recording sheets exhibiting improved toner adhesion wherein the additive components in the coating on the recording sheet which enable the improved adhesion remain within the coating when the recording sheet is stored in a vinyl or plastic folder.